This invention relates to thin film transducers of the type found in small computer disk drives.
Thin film magnetic transducers are known which are used in disk drives to write data to and read data from magnetic storage disks. A typical thin film transducer comprises a pair of pole pieces joined at a first region, usually termed the back gap region, and spaced at an opposing region, usually termed the pole tip region. In between the back gap region and the pole tip region, the pole pieces diverge in order to accommodate an electrical coil which is electrically insulated from the pole pieces. The coil is electrically connected to associated read/write circuitry. The transducer is typically fabricated on a relatively thick substrate, usually termed a slider, with the pole tip region terminating at a surface termed the air bearing surface (ABS). A typical example of such a transducer is described and illustrated in U.S. Pat. No. 4,458,279 and the additional references cited therein, the disclosures of which are hereby incorporated by reference.
Typically, a pair of such thin film transducers is fabricated on the slider surface, with each transducer located at a different end of the slider surface adjacent a lobe defined by a rail extending the entire length of the slider. Thus, in a given assembly the slider has a pair of rails running mutually parallel along the length of the slider and a thin film transducer is associated to the lobe defined by the associated rail.
The demand for increasing data density on magnetic media has lead to the requirement for substantially smaller track widths and transducers with correspondingly smaller pole tip regions. With decreasing pole tip size, the amplitude of the signal output by the transducer coil is correspondingly reduced. This is undesirable, since noise signals increasingly mask the data signals generated by the coils during a read operation, which leads to erroneous data retrieval. In the past, attempts have been made to compensate for this decrease in signal amplitude by adding more turns to a transducer coil. This solution is less than desirable, however, since it leads to an increased thickness of the transducer: in particular, in order to accommodate more turns, the coil is fabricated in several layers. This increased thickness of the transducer is highly undesirable because of a corresponding increase in noise, resistance and power consumption. Moreover, additional process steps are required, which increase production cycle time and decrease the yield rate, thereby contributing to higher cost per unit.